During production of a well, for example an oil well, the pressure from the well reservoir often becomes insufficient to transport hydrocarbons to the surface without the assistance of a pump. In such cases, a down-hole pump is typically lowered into the well, and attached to the lower end of a sucker rod string. The upper end of the rod string is then attached to a pump jack or similar reciprocating surface apparatus. Through reciprocation of the pump jack, the rod string is used to drive the down-hole pump, enabling continued production of the well.
Sucker rods are connected together in a string by connectors or end fittings attached to the ends of each rod. The end fittings comprise a rod receptacle at one end to receive the rod end, and a threaded coupling at the other end to threadingly connect to the end fitting of the next successive rod. The space between the interior wall of the rod receptacle and the external surface of the rod defines a space or annulus which is filled with epoxy or some other initially flowable adhesive similar to epoxy. The epoxy cures into a solid which bonds to the rod and takes the form of a series of wedges that cooperatively engage complementary surfaces in the rod receptacle to prevent rod pullouts (wherein the rod is pulled out of the connector rod receptacle) that would otherwise result in failure of the string.
Production of the well leads to fluids flowing in an annulus area. The annulus area is defined by the area between the sucker rod string and the well in the radial direction. The diameter of the end fittings can be a flow deterrent for fluid flowing through the annulus area. Accordingly, there is a need for an end fitting that can handle the forces and conditions encountered in the well and also allow for better fluid flow in the annulus outside of the sucker rod string.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.